1. Field of the Invention
The present invention relates to an illumination device, and more particularly, to an illumination device that guides light emitted from a light source arranged in a lateral side with respect to a light-emergent face without using a solid light guide plate, and that emits the light from the light-emergent face.
2. Description of the Related Art
Conventionally, there has been proposed a light-guide-less type illumination device, in which a light source is disposed in a lateral side with respect to a light-emergent face to guide and emit the light from the light source toward the light-emergent face, and the light passes through the air without using a solid light guide plate (refer to JP 2007-294252 A, for example).
FIG. 7 illustrates an illumination device disclosed in JP 2007-294252 A. An illumination device 100 illustrated in FIG. 7 includes a reflective body 110 obtained by laminating a reflective sheet 102 on a transparent reflection panel 101, a diffusion panel 103 arranged to face the reflective body 110 and separated from the reflective body 110 with a gap, and a light source 105 arranged in one lateral side portion between the reflective body 110 and the diffusion panel 103. In addition, the reflective body 110 is bent such that a distance between the reflective body 110 and the diffusion panel 103 is gradually reduced from one lateral side portion, where the light source 105 is arranged, to the other lateral side portion. As a result, an optical path of the light emitted from the light source 105 is directed to the diffusion panel 103 side and is emitted as an illumination light.
In general, in an illumination device, a uniform illumination intensity on an illumination target surface is important. In this regard, in the illumination device 100 disclosed in JP 2007-294252 A, a reflective face 111 of the reflection panel 101 has a concave pattern including a plurality of concave portions having a pyramid shape in order to obtain a uniform illumination intensity.